Abstract (inglese)

The idea behind concentrated photovoltaics (CPV) is straightforward: concentrate the sunlight onto a small solar cell in order to shift largest part of the system cost from the semiconductor to the balance of system components. CPV systems designed for high concentration factors use solar cells with the highest achieved efficiency, which are the triple-junction (3J) ones. The rapid growth of flat panels PV market during last years attracted the world attention to photovoltaic technologies, particularly for the achievement of the grid-parity goal. In the meanwhile CPV technology attracted researchers and investors particularly for the introduction in the PV market of high efficiency triple-junction solar cells designed for terrestrial applications. An accurate design of CPV system, pushed by a growth of the CPV market, can make CPV technology competitive in the near future. This PhD work is integrated into this research and market scenarios. The main goal of this work is to design a nonimaging optics for CPV technology. Starting from a constraint analysis of the problem some initial choices are made. This first step is also the most important one, because it needs a deep knowledge of the technologies involved, from the mechanical tolerances to the production costs. At this level a key choice is the main optical element, which in this work is a polycarbonate substrate that is then aluminized. This choice was made basically to take advantage of injection molding technology know-how, particularly for automotive lighting application. After these initial choices a work flow is adopted for the subsequent design of the optical scheme, the tolerance analysis and the manufacturing process, analyzing carefully in particular the realization of the primary optical element. For this purpose a dedicated experiment was performed in order to optimize its injection molding process. The work concludes with an outdoor test of the first prototype manufactured and with a comparison of its performances with the electrical distributed model developed. All the activities presented were supported by Polo Fotovoltaico Veneto and Centro Studi e Ricerche E.Fermi of Rome. The outdoor measurements on the experimental installations were performed within the Laboratori Nazionali di Legnaro (LNL-INFN), while the experiment designed around the injection mold was performed within the company Unica Srl in Conegliano Veneto, Treviso.